46 research outputs found
Lattice renormalisation of O(a) improved heavy-light operators: an addendum
The analytical expressions and the numerical values of the renormalisation
constants of dimension 3 static-light currents are given at one-loop order of
perturbation theory in the framework of Heavy Quark Effective Theory and with
an improved gauge action: the static quark is described by the HYP-smeared
action and the light quark is of Wilson kind. This completes a work started few
years ago and is actually an intermediate step in the measurement of the decay
constants and by the European Twisted Mass Collaboration
[arXiv:1107.1441[hep-lat]].Comment: 5 pages, no figure
Density distributions in the meson
We report on a two-flavor lattice QCD study of the axial, charge and matter
distributions of the meson and its first radial excitation. As our
framework is the static limit of Heavy Quark Effective Theory (HQET), taking
their Fourier transform gives access to several form factors at the kinematical
point . Moreover they provide some useful information on the nature of
an excited state, i.e. a radial excitation of a quark-antiquark bound state or
a multihadron state.Comment: 26 pages, 25 figures, 12 tables; published versio
Pion couplings to the scalar B meson
We present two-flavor lattice QCD estimates of the hadronic couplings
and that parametrise the non leptonic
decays and . We use CLS two-flavour
gauge ensembles. Our framework is the Heavy Quark Effective Theory (HQET) in
the static limit and solving a Generalized Eigenvalue Problem (GEVP) reveals
crucial to disentangle the () state from the ()
state. This work brings us some experience on how to treat the possible
contribution from multihadronic states to correlation functions calculated on
the lattice, especially when -wave states are involved.Comment: 12 pages, 10 figures, published versio
Lattice renormalisation of O(a) improved heavy-light operators
The analytical expressions and the numerical values of the renormalisation
constants of improved static-light currents are given at one-loop
order of perturbation theory in the framework of Heavy Quark Effective Theory:
the static quark is described by the HYP action and the light quark is
described either with the Clover or the Neuberger action. These factors are
relevant to extract from a lattice computation the decay constants ,
and the set of bag parameters associated with
mixing phenomenology in the Standard Model and beyond.Comment: 16 pages, 2 figures, 4 tables; few comments and references added;
version to be published in Phys Rev
Renormalization of quark propagator, vertex functions and twist-2 operators from twisted-mass lattice QCD at =4
We present a precise non-perturbative determination of the renormalization
constants in the mass independent RI'-MOM scheme. The lattice implementation
uses the Iwasaki gauge action and four degenerate dynamical twisted mass
fermions. The gauge configurations are provided by the ETM Collaboration.
Renormalization constants for scalar, pseudo-scalar, vector and axial
operators, as well as the quark propagator renormalization, are computed at
three different values of the lattice spacing, two volumes and several twisted
mass parameters. The method we developed allows for a precise cross-check of
the running, thanks to the particular proper treatment of hypercubic artifacts.
Results for the twist-2 operator are also presented.Comment: 20 pages, 20 figures, submitted to Phys. Rev.
The distribution amplitude of the meson
We report on the first lattice determination of the pseudoscalar meson
light-cone distribution amplitude, using a set of three CLS
ensembles at a pion mass and lattice spacings , and . Employing Short
Distance Factorization, we extract the pseudo-DA on the lattice for Ioffe times
, and the various lattice spacings allow us to take the continuum
limit. We employ a basis of Jacobi polynomials to parametrize the distribution
amplitude, which allows to express the matching to the pseudo distribution in
closed form, and we observe a strong effect which we attribute to the heavy
charm-quark mass.Comment: Contribution to the 40th International Symposium on Lattice Field
Theory (Lattice 2023), July 31st - August 4th, 2023. Fermi National
Accelerator Laborator
B-meson spectroscopy in HQET at order 1/m
35 pages, 14 tables, 17 figures; Introduction extended and typos corrected. Version accepted for publication in PRDWe present a study of the B spectrum performed in the framework of Heavy Quark Effective Theory expanded to next-to-leading order in 1/m and non-perturbative in the strong coupling. Our analyses have been performed on Nf=2 lattice gauge field ensembles corresponding to three different lattice spacings and a wide range of pion masses. We obtain the Bs-meson mass and hyperfine splittings of the B- and Bs-mesons that are in good agreement with the experimental values and examine the mass difference m_{Bs}-m_B as a further cross-check of our previous estimate of the b-quark mass. We also report on the mass splitting between the first excited state and the ground state in the B and Bs systems
HQET at order : II. Spectroscopy in the quenched approximation
Using Heavy Quark Effective Theory with non-perturbatively determined
parameters in a quenched lattice calculation, we evaluate the splittings
between the ground state and the first two radially excited states of the
system at static order. We also determine the splitting between first excited
and ground state, and between the and ground states to order
. The Generalized Eigenvalue Problem and the use of all-to-all
propagators are important ingredients of our approach.Comment: (1+18) pages, 3 figures (4 pdf files); pdflatex; v2: corrections to
table 1, results unaffecte